<template>
  <h3>孙组件</h3>
  <h4>a：{{ a }}</h4>
  <h4>b：{{ b }}</h4>
  <button @click="updateA(1)">点我更新A</button>
</template>

<script setup>
defineProps(['a', 'b', 'updateA'])
</script>

<style lang="scss" scoped></style>
